Many liquid pumping systems have means for entrapping and compressing air in order to generate rotational mechanical energy. However, most traditional designs required a naturally occurring steep vertical fall that is fed by a stream of water, such as a waterfall, in order to be operational. This required that the water source must be located on ground having a high altitude and the compressed gas accumulator must be located on ground having a lower altitude. In conventional systems, water expelled from the system is returned to the moving water source at a return location that is different from the location that feeds the system, i.e., the water return point has a lower altitude than the point where water is taken from the stream to fill the conventional system. These geographic constraints drastically limited the areas that many hydraulic air compressor systems could be located. Furthermore, water passing through a traditional liquid pumping system could be used only once, thereby requiring a continuous renewable resource of liquid to drive the system. Accordingly, a need remains for a liquid pumping system that uses compressed gas to drive a mechanical device that does not require a continuous renewable water source. The present invention has been developed in view of the foregoing.